This invention relates to networks and more particularly, to a bridging and switching methodology, architecture, and protocol for bridging a plurality of networks and a shared core system with interface adapters, coupled via a unique multiple bus architecture and protocol, and bus management.
Existing networks include analog (e.g., voice, composite video, etc.), and video, and can be coupled any of numerous ways including electrically and optically, and can be direct physically coupled or wireless broadcast.
Numerous products exist to permit switching across and among a plurality of similar type individual networks. One class of products are bus adapters. Bus adapters permit switching between different bus architectures. For instance, given a Nubus in the Apple Macintosh architecture and an Sbus in the Sun Spark Station architecture, the two buses could be connected together to a bus adapter that converted both the data architecture from either the Nubus or the Sbus to the other and the physical signal level on each bus. Switching across networks may also be accomplished through conventional communication protocols. Ethernet, FDDI, TCP/IP, SCSI, and the RS-232-C serial interface can perform the function of connecting disparate systems. Although these protocols are often slow and complex, they're well understood, standardized, and well documented. Protocol converters permit a hardwired interface between different protocol interface architectures, such as Ethernet to serial.
Difficulties arise in attempting to integrate dissimilar types of network computers, data, voice, airwave broadcast, cable systems (having very high bandwidth capacity), telephone long lines, fiber optics, lease lines, etc.
A standard was achieved defining a framework from which individual designers could create their own individual solutions to implement and build from and onto an agreed upon basic specification for Asynchronous Transfer Mode (ATM) technology. By adhering to a predefined nucleus of selected common passing criteria, dissimilar data architecture and protocol systems are allowed to independently communicate along a common pathway.
Publication of Asynchronous Transfer Mode technology literature is plentiful, and is incorporated herein by reference, including the following:
ATM Forum, "User-to-Network Interface (UNI) Specification", Version 3.0 (UNI Spec.).
ATM Forum, "LAN Emulation (LANE) Specification", Version 1.0
Case et al., "Simple Network Management Protocol (SNMP)", 1990 May (RFC 1157).
Draft Recommendation 1.150, B-ISDN ATM Functional Characteristics, CCITT SG XVIII, Report R34, June 1990.
C. A. Sunshine, ed., Computer Network Architectures and Protocols (Plenum, N.Y.).
Stassinopoulos et al., "ATM Adaptation Layer Protocols for Signalling", Computer Networks ISDN Systems, 23 (4) (1992), pp. 287-304.
Pirat, P., "Synchronization and Error Recovery in Video Terminal Adapters in an ATM Environment", Race 1022 Workshop, Paris, October 1989, CNET.
Fuhrmann et al., "Burst and Cell Level Models for ATM Buffers", IBM Research Report RZ 2014, August 1990.
Eckbert et al., "An Approach to Controlling Congestion in ATM Networks", U-Dacs, 3 (2) (1990), pp. 199-209.
Various forays into attempting to build an ATM compatible product have yielded patchwork solutions, incomplete in their compliance with the ATM specification. In modifying existing systems, many constraints are placed on the implementation alternatives a designer can use. Nonetheless, many creative designs have evolved to permit limited access into ATM for existing computer and other data network users. Systems of this type include ATM systems or ATM bridging systems developed by Fore Systems, Newbridge, and Cisco. Fore Systems and Newbridge specialize in ATM systems, while Cisco builds routers. In addition, companies such as NetEdge build devices that multiplex multiple Ethernet ports onto a wide area network. The disadvantage of the NetEdge system is that they mix multiple users' data much as a router would mix the data.
In attempting to implement a real system solution to ATM compatibility and simultaneously provide a bridge between dissimilar network structures, many problems are encountered. A key one is the need for a very high bandwidth bus architecture to support very high speed communications to and from each of the attached network Interface Adapters. Numerous problems exist in the various combinations of choices for obtaining high bandwidth communication between attached input/output Interface Adapters and/or a central switch core which coordinates and manages ATM traffic, including but not limited to cell flow prioritization, bus arbitration, etc. Various problems also exist with regard to bus management. Where multiple Adapters simultaneously contend for a given bus, management of collision allocation, frequency and duration, all present problems.